Tantalum spinneret



Feb. 1-0, 1931. M. M. AUSTIN TANTALUM SPINNERET Original Filed June 2.1928 Patented Feb. 10, 1931 UNITED Sra'rss MINER M. AUSTIN, or WAUKEGAN,ILLINOIS ASSIGNOR 'rojIiANs'rEEn PRODUCTS COMPANY, INC., OI` NORTHCHICAGO, ILLINOIS, A ConroRe'rIoN or ILLINOIS TANTALUM SPINNERETApplication filed .Tune 2, 1928, Serial No. 282,490. Renewed October,27, 1930.

spinneret of tantalum which is coated by al hard electrolytic filmwhereby the minute openings are' not distorted or worn out of shape bycontinued usage. The object of this invention is to providera spinneretwhich will not be corroded either in the fluids in which the spinneretis finally used or in thek fluid used to dissolve the cores in obtainingthe minute openings.

A. further object is to provide a spinneret with a hard enamel-likeiilmxwhereby the shape of the openings are not irregularly worn.

Other objects of my invention will be apparent as thev detaileddescription of my invention proceeds.

A preferred embodiment of the invention is illustrated in theaccompanying drawing wherein similarparts are designated by likereference characters throughout the several views and wherein Fig. l isa perspective of my improved spinneret having a portion broken or outaway to show the construction thereof.

k Fig. 2 is a diagrammatic representation of the film forming bath.

The manufacture of artificial silk or rayon requiresy the use ofspinnerets which have very fine Openings and in which the openings arecircular. If the openings are distorted or flat therayon produced Vwillbe of an inferior quality and will only demand about One-third of themarket price.

Heretofore such spiunerets have been made of platinum, platinum goldalloys, etc., because these were the only metals known which combinedsuitable acid resisting qualities with a malleability and hardness whichwould permit the drilling of the extremely small holes and which wouldprevent these holes from being deformed by usage. Tantalum had beentried without success because the metal was so hard that the holes couldnot be properly drilled. If the metal were softened or annealed toovercome this difliculty the holes were likelyT to be deformed bysubsequent use.

l have discovered that by coating the spinE neret with anelectrolytic-film, a hardenamellike surface is formed' thereon which isY of infinitesimal thickness, but which, .nevertheless, is extremelyresistant and'which renders thespinneretpractically impervious tocorrosive action and to the erosion` orv wearing awayidue tocontinuedusage.

In Fig. l I have shown a spinneret l0 of conventional type which isprovided with ay face plate ll'in which are drilled a plurality of holes13.

Since the tantalum must be relativelymaL leable to permit forming theholes 13 therein, it is necessary that its surface be hardened if it isto resistthe wear to which it must be subjected. To accomplish this Iimmerse the spinneret in sulphuric acid bath (specific gravity about1.250) and subject it to an electric potential of about 2O to 110 volts.The

time of immersion will necessarily vary with the immersed area of thespinneret but I have found that by using alternating current of 110volts the proper film is formed on an area of 10 square inches bysubjecting it to this potential for about 30 seconds, a resistance ofabout 8O ohms being in the circuit as shown in Fig. 6.

A simple apparatus for electrolytically filming the spinneret consistsof a suitable metallic receptacle 18 containing sulphuric acid 19. 'Ihecontainer is connected by a conductor 2O to an alternating currentsource l which is, in turn, connected by'conductor 22 to variableresistance 23, this resistance being connected by conductor 24 to thespinneret as shown in Fig. 6. The resistance in Vmy preferred embodimentis about 80 ohms and the alternating current source is' 110 PAT-ENIorsi-Scsi,

infinitesimal thickness, said lm also serving to protect the openingsinthe face of the spinneret as shown in Fig. 1. The electrolytic filmnot only increases the hardness and wear resista-nce of the metal but itprovides a highly decorative film of vari-colored irridescentV nature,which is characteristic of this metal. The decorative feature, however',forms no part of the present invention.

While I have described a preferred embodiment of my invention it isunderstood that I am not limited to the details thereof, except asconfined by the following claim.

An article of manufacture comprising a tantalum spinneret and a hardresistant oxide film formed directly thereon whereby said tantalumspinneret is protected against corrosion and wear.

In witness whereof, I hereunto subscribe my name this 24th day of May,1928.

MINER M. AUSTIN.

